Syrian rebels have captured a key regime artillery base and secured control
of several of the country’s lucrative oilfields, bringing a large part of
the border region with Iraq under their control.

Rebels overran the army base on the outskirts of Mayadeen town in Deir al-Zour province on Thursday morning, loosening the government's control on a region that acts as a key supply route for the opposition, bringing fighters and weapons from neighbouring Iraq.

"The military base was liberated early this morning. It was under siege for 15 days," said an activist calling himself Mohammed Saleh who works with the opposition Local Coordinating Committee for the province. "This is the last military base in the countryside. Now the territory is liberated all the way to the borders with Iraq."

Opposition fighters are increasingly on the offensive. The capture of the artillery base follows takeovers of army installations in the north and centre of the country.

Mr Salah said the government's elite Presidential Guards were pulled back from Deir al-Zour to reinforce defences in the capital earlier this month, after the opposition declared the "March on Damascus" offensive.

Troops also pulled back from three positions south of the town of Maarat al-Numan, on the highway linking Damascus to Aleppo, according to the opposition Syrian Network for Human Rights.

Government troops still remain in districts of Deir al-Zour city and are waging a bitter offensive to keep control. Residents said the fighting had destroyed much of the city and left the population living in dire conditions: "There is shelling night and day. The bridges that cross the Euphrates River and connect the city together have been targeted by air strikes and destroyed," said a young resident using the name Abu Wissam.

"There are serious food shortages, and there is little water and electricity so even if we get the raw materials we can't cook. The only one running is the government military hospital and it is offering no help to civilians. Our field hospitals are often bombed."

There are signs that months of fighting are taking their toll on the government's hold on the country. Controlling Deir al-Zour province means controlling the country's main oil reserves. Two out three of the largest fields are now in opposition hands, with rebels and profiteers extracting oil: "Looters are selling the fuel back to the local population," said a resident calling himself Abdel Azziz. "It is crude oil, but people are desperate and need it to heat homes and cook".

Separately, in what appears to be an increasingly common tactic, fighter jets targeted the main field hospital in opposition-held Aleppo on Wednesday evening. The strike flattened the building next to the hospital, killing at least 11 people, including a doctor and two children, activists reported, although some said the death toll was higher.